Catalyst and process for preparing low-viscosity and color-reduced polyisocyanates containing isocyanurate groups

Abstract

A low-viscosity polyisocyanate of reduced color, containing isocyanurate groups is prepared by partially trimerizing an aliphatic and/or cycloaliphatic diisocyanate in the presence of 0.02 to 2% weight, based on the weight of the diisocyanate starting material, of at least one trimerization catalyst containing a quarternary amine component and then removing excess diisocyanate from the reaction medium.

1. A trimerization catalyst, comprising a compound selected from the group consisting of benzyldimethylethylammonium pivalate, benzyldimethylethylammonium 2-ethylhexanoate, benzyltributylammonium 2-ethylhexanoate, N,N-dimethyl-N-ethyl-N-(4-methoxybenzyl)ammonium-2-ethylhexanoate, or N,N,N-tributyl-N-(4-methoxybenzyl)ammonium pivalate. 
     
     
       2. A process for preparing a trimerization catalyst comprising:
 quaternizing a tertiary amine with an alkylating agent thereby forming a quaternary benzylammonium compound; and  
 converting the quaternary benzylammonium compound into the corresponding carboxylate salt;  
 wherein said alkylating agent is selected from the group consisting of Meerwein salts;  
 thereby obtaining said trimerization catalyst which is a compound of formula (I): 
                 
 
 
       and wherein substituents A, B, C, D, and E simultaneously or independently of one another are hydrogen, chloro, C 1 -C 4 -alkyl, C 1 -C 4 -alkoxy, C 1 -C 4 -alkoxycarbonyl, hydroxyl, (R 5 ) 3 SiO—, (R 5 ) 2 N—, COOH, (R 5 ) 2 N—CH 2 - or phenyl, it being 5 possible for any two adjacent radicals selected from the group A, B, C, D and E to form a conjoint 5- or 6-membered saturated or unsaturated ring which may also include nitrogen, sulfur or oxygen heteroatoms;
 F is hydrogen, methyl or fluoro;  
 G is hydrogen, methyl or fluoro;  
 R 2  and R 3  simultaneously or independently of one another are C 1 -C 18 -alkyl or R 1 ;  
 R 4  is hydrogen, methyl, C 2 -C 18 -alkyl, C 3 -C 8 -cycloalkyl or C 2 -C 12 -alkoxy;  
 R 5  is C 1 -C 18 -alkyl;  
 Y— is R 6 COO—;  
 R 6  is hydrogen or a branched or unbranched aliphatic or araliphatic C 1 -C 12 -alkyl radical.  
 
     
     
       3. The process according to  claim 2 , wherein said tertiary amine is selected from the group consisting of trimethylamine, triethylamine, dimethylethylamine, diethylmethylamine, tripropylamine, tributylamine, trioctylamine, tridodecylamine, N,N-dimethylallylamine, N,N-diethylallylamine, N-ethyl-N-methylallylamine, N,N-dimethylmethallylamine, N,N-diethylmethallylamine, dimethyldodecylamine, diethyldodecylamine, dipropyldodecylamine, dibutyldodecylamine, didodecylmethylamine, didodecylethylamine, didodecylpropylamine, didodecylbutylamine, N,N-dimethyl-2-methoxybenzylamine, N,N-dimethyl-3-methoxybenzylamine, N,N-dimethyl-4-methoxybenzylamine, N,N-dimethyl-2,3-dimethoxybenzylamine, N,N-dimethyl-3,4-dimethoxybenzylamine, N,N-dimethyl-3,5-dimethoxybenzylamine, N,N-dimethylbenzylamine, N,N-dimethylbenzylamine-4-carbonitrile, 4-methoxycarbonyl-N,N-dimethylbenzylamine, 4-ethoxycarbonyl-N,N-dimethylbenzylamine, 3-(N,N-dimethylaminomethyl)-N,N-dimethylbenzylamine, 1-phenylethyldimethylamine, 4-hydroxy-N,N-dimethylbenzylamine, 4-trimethylsiloxy-N,N-dimethylbenzylamine, and N,N-dimethylnaphthylamine. 
     
     
       4. The process according to  claim 2 , wherein said alkylating agent is selected from the group consisting of alkyl halides, benzyl halides, alkyl triflates, benzyl triflates, alkyl tosylates and benzyl tosylates. 
     
     
       5. The process according to  claim 2 , wherein said alkylating agent is selected from the group consisting of methyl iodide, methyl bromide, methyl chloride, methyl triflate, methyl tosylate, ethyl iodide, ethyl bromide, ethyl chloride, ethyl triflate, ethyl tosylate, butyl iodide, butyl bromide, butyl chloride, butyl triflate, butyl tosylate, dodecyl iodide, dodecyl bromide, dodecyl chloride, dodecyl triflate, dodecyl tosylate, allyl iodide, allyl bromide, allyl chloride, allyl triflate, allyl tosylate, benzyl iodide, benzyl bromide, benzyl chloride, benzyl triflate, benzyl tosylate, 4-chlorobenzyl iodide, 4-chlorobenzyl bromide, 4-chlorobenzyl chloride; 4-chlorobenzyl triflate, 4-chlorobenzyl tosylate, 2-chlorobenzyl iodide, 2-chlorobenzyl bromide, 2-chlorobenzyl chloride, 2-chlorobenzyl triflate, 2-chlorobenzyl tosylate, methallyl iodide, methallyl bromide, methallyl chloride, methallyl triflate, methallyl tosylate, 4-methoxycarbonylbenzyl iodide, 4-methoxycarbonylbenzyl bromide, 4-methoxycarbonylbenzyl chloride, 4-methoxycarbonylbenzyl triflate, 4-methoxycarbonylbenzyl tosylate, 4-methoxybenzyl iodide, 4-methoxybenzyl bromide, 4-methoxybenzyl chloride, 4-methoxybenzyl triflate, 4-methoxybenzyl tosylate, 4-methylbenzyl iodide, 4-methylbenzyl bromide, 4-methylbenzyl chloride, 4-methylbenzyl triflate, 4-ethylbenzyl tosylate, 3-methylbenzyl iodide, 3-methylbenzyl bromide, 3-methylbenzyl chloride, 3-methylbenzyl triflate, 3-methylbenzyl tosylate, 2-methylbenzyl iodide, 2-methylbenzyl bromide, 2-methylbenzyl chloride, 2-methylbenzyl triflate, and 2-methylbenzyl tosylate. 
     
     
       6. The process according to  claim 2 , wherein said Meerwein salts are trimethyloxonium tetrafluoroborate or triethyloxonium tetrafluoroborate. 
     
     
       7. The process according to  claim 2 , wherein said quaternizing of the tertiary amine takes place at from 0 to 100° C. 
     
     
       8. The process according to  claim 2 , wherein said quaternizing is carried out in the presence of a solvent. 
     
     
       9. The process according to  claim 2 , wherein said quaternizing is carried out in the absence of a solvent. 
     
     
       10. The process according to  claim 8 , wherein said solvent is selected from the group consisting of acetonitrile, dimethylformamide, dimethyl sulfoxide, acetone, 2-ethylhexanediol, and dichloromethane. 
     
     
       11. The process according to  claim 2 , wherein said converting of said quaternary benzylammonium compound is performed by ion exchange chromatography. 
     
     
       12. The process according to  claim 2 , wherein said carboxylate salt is obtained from a carboxylic acid selected from the group consisting of pivalic acid, hexanoic acid, acetic acid, 2-ethylhexanoic acid, propanoic acid, adipic acid, succinic acid, and oleic acid. 
     
     
       13. A method for trimerizing diisocyanates, comprising:
 trimerizing diisocyanates in the presence of a trimerization catalyst which is a compound of formula (I): 
                 
 
 
       and wherein substituents A, B, C, D, and E simultaneously or independently of one another are hydrogen, chloro, C 1 -C 4 -alkyl, C 1 -C 4 -alkoxy, C 1 -C 4 -alkoxycarbonyl, hydroxyl, (R 5 ) 3 SiO—, (R 5 ) 2 N—, COOH, (R 5 ) 2 N—CH 2 - or phenyl, it being 5 possible for any two adjacent radicals selected from the group A, B, C, D and E to form a conjoint 5- or 6-membered saturated or unsaturated ring which may also include nitrogen, sulfur or oxygen heteroatoms;
 F is hydrogen, methyl or fluoro;  
 G is hydrogen, methyl or fluoro;  
 R 2  and R 3  simultaneously or independently of one another are C 1 -C 18 -alkyl or R 1 ;  
 R 4  is hydrogen, methyl, C 2 -C 18 -alkyl, C 3 -C 8 -cycloalkyl or C 2 -C 2 -alkoxy;  
 R 5  is C 1 -C 18 -alkyl;  
 Y-is R 6 COO—;  
 R 6  is hydrogen or a branched or unbranched aliphatic or araliphatic C 1 -C 2 -alkyl radical.  
 
     
     
       14. A process for preparing a trimerization catalyst, comprising:
 quaternizing a tertiary amine with an alkylating agent thereby forming a quaternary benzylammonium compound; and  
 converting the quaternary benzylammonium compound into the corresponding carboxylate salt;  
 wherein said converting of said quaternary benzylammonium compound is performed by ion exchange chromatography;  
 thereby obtaining said trimerization catalyst which is a compound of formula (I): 
                 
 
 
       and wherein substituents A, B, C, D, and E simultaneously or independently of one another are hydrogen, chloro, C 1 -C 4 -alkyl, C 1 -C 4 -alkoxy, C 1 -C 4 -alkoxycarbonyl, hydroxyl, (R 5 ) 3 SiO—, (R 5 ) 2 N—, COOH, (R 5 ) 2 N—CH 2 - or phenyl, it being 5 possible for any two adjacent radicals selected from the group A, B, C, D and E to form a conjoint 5- or 6-membered saturated or unsaturated ring which may also include nitrogen, sulfur or oxygen heteroatoms;
 F is hydrogen, methyl or fluoro;  
 G is hydrogen, methyl or fluoro;  
 R 2  and R 3  simultaneously or independently of one another are C 1 -C 18 -alkyl or R 1 ;  
 R 4  is hydrogen, methyl, C 2 -C 18 -alkyl, C 3 -C 8 -cycloalkyl or C 2 -C 12 -alkoxy;  
 R 5  is C 1 -C 18 -alkyl;  
 Y-is R 6 COO—;  
 R 6  is hydrogen or a branched or unbranched aliphatic or araliphatic C 1 -C 12 -alkyl radical.  
 
     
     
       15. The process according to  claim 14 , wherein said tertiary amine is selected from the group consisting of trimethylamine, triethylamine, dimethylethylamine, diethylmethylamine, tripropylamine, tributylamine, trioctylamine, tridodecylamine, N,N-dimethylallylamine, N,N-diethylallylamine, N-ethyl-N-methylallylamine, N,N-dimethylmethallylamine, N,N-diethylmethallylamine, dimethyldodecylamine, diethyldodecylamine, dipropyldodecylamine, dibutyldodecylamine, didodecylmethylamine, didodecylethylamine, didodecylpropylamine, didodecylbutylamine, N,N-dimethyl-2-methoxybenzylamine, N,N-dimethyl-3-methoxybenzylamine, N,N-dimethyl-4-methoxybenzylamine, N,N-dimethyl-2,3-dimethoxybenzylamine, N,N-dimethyl-3,4-dimethoxybenzylamine, N,N-dimethyl-3,5-dimethoxybenzylamine, N,N-dimethylbenzylamine, N,N-dimethylbenzylamine-4-carbonitrile, 4-methoxycarbonyl-N,N-dimethylbenzylamine, 4-ethoxycarbonyl-N,N-dimethylbenzylamine, 3-(N,N-dimethylaminomethyl)-N,N-dimethylbenzylamine, 1-phenylethyldimethylamine, 4-hydroxy-N,N-dimethylbenzylamine, 4-trimethylsiloxy-N,N-dimethylbenzylamine, and N,N-dimethylnaphthylamine. 
     
     
       16. The process according to  claim 14 , wherein said alkylating agent is selected from the group consisting of alkyl halides, benzyl halides, alkyl triflates, benzyl triflates, alkyl tosylates and benzyl tosylates. 
     
     
       17. The process according to  claim 14 , wherein said alkylating agent is selected from the group consisting of methyl iodide, methyl bromide, methyl chloride, methyl triflate, methyl tosylate, ethyl iodide, ethyl bromide, ethyl chloride, ethyl triflate, ethyl tosylate, butyl iodide, butyl bromide, butyl chloride, butyl triflate, butyl tosylate, dodecyl iodide, dodecyl bromide, dodecyl chloride, dodecyl triflate, dodecyl tosylate, allyl iodide, allyl bromide, allyl chloride, ally triflate, ally tosylate, benzyl iodide, benzyl bromide, benzyl chloride, benzyl triflate, benzyl tosylate, 4-chlorobenzyl iodide, 4-chlorobenzyl bromide, 4-chlorobenzyl chloride; 4-chlorobenzyl triflate, 4-chlorobenzyl tosylate, 2-chlorobenzyl iodide, 2-chlorobenzyl bromide, 2-chlorobenzyl chloride, 2-chlorobenzyl triflate, 2-chlorobenzyl tosylate, methallyl iodide, methallyl bromide, methallyl chloride, methallyl triflate, methallyl tosylate, 4-methoxycarbonylbenzyl iodide, 4-methoxycarbonylbenzyl bromide, 4-methoxycarbonylbenzyl chloride, 4-methoxycarbonylbenzyl triflate, 4-methoxycarbonylbenzyl tosylate, 4-methoxybenzyl iodide, 4-methoxybenzyl bromide, 4-methoxybenzyl chloride, 4-methoxybenzyl triflate, 4-methoxybenzyl tosylate, 4-methylbenzyl iodide, 4-methylbenzyl bromide, 4-methylbenzyl chloride, 4-methylbenzyl triflate, 4-ethylbenzyl tosylate, 3-methylbenzyl iodide, 3-methylbenzyl bromide, 3-methylbenzyl chloride, 3-methylbenzyl triflate, 3-methylbenzyl tosylate, 2-methylbenzyl iodide, 2-methylbenzyl bromide, 2-methylbenzyl chloride, 2-methylbenzyl triflate, and 2-methylbenzyl tosylate. 
     
     
       18. The process according to  claim 14 , wherein said alkylating agent is selected from the group consisting of Meerwein salts. 
     
     
       19. The process according to  claim 18 , wherein said Meerwein salts are trimethyloxonium tetrafluoroborate or triethyloxonium tetrafluoroborate. 
     
     
       20. The process according to  claim 14 , wherein said quaternizing of the tertiary amine takes place at from 0 to 100° C. 
     
     
       21. The process according to  claim 14 , wherein said quaternizing is carried out in the presence of a solvent. 
     
     
       22. The process according to  claim 14 , wherein said quaternizing is carried out in the absence of a solvent. 
     
     
       23. The process according to  claim 21 , wherein said solvent is selected from the group consisting of acetonitrile, dimethylformamide, dimethyl sulfoxide, acetone, 2-ethylhexanediol, and dichloromethane. 
     
     
       24. The process according to  claim 14 , wherein said carboxylate salt is obtained from a carboxylic acid selected from the group consisting of pivalic acid, hexanoic acid, acetic acid, 2-ethylhexanoic acid, propanoic acid, adipic acid, succinic acid, and oleic acid. 
     
     
       25. The process as claimed in  claim 2 , wherein the substituents of formula (I) have the following definitions:
 A: methyl, methoxy, H;  
 B: H;  
 C: methyl, methoxy, H;  
 D: H;  
 E: methyl, methoxy, H;  
 F: H, methyl;  
 G: H, methyl;  
 R 2 , R 3 : R 1  or methyl, ethyl, propyl, butyl, pentyl, hexyl;  
 R 4 , R 5 : methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclohexyl;  
 R 6 : tert-butyl, pentyl, isopentyl, hexyl, isohexyl, ethylpentyl, isoheptyl.  
 
     
     
       26. The process as claimed in  claim 13 , wherein the substituents of formula (I) have the following definitions:
 A: methyl, methoxy, H;  
 B: H;  
 C: methyl, methoxy, H;  
 D: H;  
 E: methyl, methoxy, H;  
 
       F: H, methyl;
 G: H, methyl;  
 R 2 , R 3 : R 1  or methyl, ethyl, propyl, butyl, pentyl, hexyl;  
 R 4 , R 5 : methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclohexyl;  
 R 6 : tert-butyl, pentyl, isopentyl, hexyl, isohexyl, ethylpentyl, isoheptyl.  
 
     
     
       27. The process as claimed in  claim 14 , wherein the substituents of formula (I) have the following definitions:
 A: methyl, methoxy, H;  
 B: H;  
 C: methyl, methoxy, H;  
 D: H;  
 E: methyl, methoxy, H:  
 F: H, methyl;  
 G: H, methyl  
 R 2 , R 3 : R 1  or methyl, ethyl, propyl, butyl, pentyl, hexyl;  
 R 4 , R 5 : methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclohexyl;  
 R 6 : tert-butyl, pentyl, isopentyl, hexyl, isohexyl, ethylpentyl, isoheptyl.